(I’m working the front counter. A customer comes inside carrying one of our large cups of soda. She pushes past several other customers who are waiting in line and slams the cup down onto the counter.)

Customer: “I just came through the drive-thru and they f***ed up my order yet again! It’s not that hard, so I don’t know why you idiots can’t handle it.”

Me: “Sorry about that. What were you missing?”

Customer: “Nothing! It’s my drink! I ordered a large Diet Coke with the ice on the bottom.”

(She rips the lid off of the cup. As one would expect from any soda currently obeying the laws of physics, the ice is floating on the top.)

Customer: “What does that look like to you?!”

Me: “Well, it looks like the ice is floating on the top.”

Customer: “Exactly! You’re going to dump this out and remake it, with the ice on the bottom this time!”

Me: “I’m not sure that’s possible. Ice floats, ma’am. I can’t make it stay on the bottom of the cup.”

Customer: “What are you talking about? Just put the ice in the bottom of the cup.”

Me: “But when I fill it with soda, the ice is going to float up to the top anyway. It’s just how it works.”

Customer: “You don’t know what you’re talking about. Just make it work.”

Me: “I’m sorry, maybe I’m just not understanding you. If you could just show me over at the self-serve drink station, I can tell everyone else how to do it properly next time.”

(The customer storms over to the station and empties her cup. She proceeds to fill the cup with ice, casting me smug looks over her shoulder, and then dispenses soda into the cup. When it is full, she looks down at the cup in disbelief. The customer dumps out her soda and makes another attempt. After three or four tries, she finally caps the cup again and walks out of the store, avoiding eye contact with me.)